原生js页面滚动延迟加载图片_javascript技巧

本文实例为大家讲解了javascript瀑布流代码，即js页面滚动延迟加载图片，分享给大家供大家参考，具体代码如下

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>原生Js页面滚动延迟加载图片</title>
<style type="text/css">
*
{
 margin:0;
 padding:0
}
img.scrollLoading
{
 border:1px solid #ccc;
 display:block;
 margin-top:10px;
}
</style>
</head>
<body>
<div id="content"></div>
</body>
</html>
<script type="text/javascript">
var _CalF = {
 $:function(object){//选择器
 if(object === undefined ) return;
 var getArr = function(name,tagName,attr){
 var tagName = tagName || '*',
 eles = document.getElementsByTagName(tagName),
 clas = (typeof document.body.style.maxHeight === "undefined") ? "className" : "class";//ie6
 attr = attr || clas,
 Arr = [];
 for(var i=0;i<eles.length;i++){
 if(eles[i].getAttribute(attr)==name){
 Arr.push(eles[i]);
 }
 }
 return Arr;
 };
 if(object.indexOf('#') === 0){ //#id
 return document.getElementById(object.substring(1));
 }
 else if(object.indexOf('.') === 0){ //.class
 return getArr(object.substring(1));
 }
 else if(object.match(/=/g)){ //attr=name
 return getArr(object.substring(object.search(/=/g)+1),null,object.substring(0,object.search(/=/g)));
 }
 else if(object.match(/./g)){ //tagName.className
 return getArr(object.split('.')[1],object.split('.')[0]);
 }
 },
 getPosition : function(obj) { //获取元素在页面里的位置和宽高
 var top = 0,
 left = 0,
 width = obj.offsetWidth,
 height = obj.offsetHeight;
 while(obj.offsetParent){
 top += obj.offsetTop;
 left += obj.offsetLeft;
 obj = obj.offsetParent;
 }
 return {"top":top,"left":left,"width":width,"height":height};
 }
}; 

//添加图片list
var _temp = [];
for (var i = 1; i < 21; i ++) {
 _temp.push('<img class="scrollLoading" data-src="http://images.cnblogs.com/cnblogs_com/Darren_code/311197/o_' + i + '.jpg" src=https://yunqi-tech.oss-cn-hangzhou.aliyuncs.com/23160223-c81dd9aa9a2a4071a47b0ced2c9118bc.gif /><br />图片' + i);
}
_CalF.$("#content").innerHTML = _temp.join(""); 

function scrollLoad(){
 this.init.apply(this, arguments);
}
scrollLoad.prototype ={
 init : function(className){
 var className = "img."+className,
 imgs = _CalF.$(className),
 that = this;
 this.imgs = imgs;
 that.loadImg();
 window.onscroll = function(){
 that.time = setTimeout(function(){
 that.loadImg();
 },400);
 }
},
loadImg : function(){
var imgs = this.imgs.reverse(), //获取数组翻转
len = imgs.length;
if(imgs.length===0){
 clearTimeout(this.time);
 return;
}
for(var j=len-1;j>=0;j--){ //递减
 var img = imgs[j],
 imgTop = _CalF.getPosition(img).top,
 imgSrc = img.getAttribute("data-src"),
 offsetPage = window.pageYOffset ? window.pageYOffset : window.document.documentElement.scrollTop,//滚动条的top值
 bodyHeight = document.documentElement.clientHeight; //body的高度
 if((offsetPage+bodyHeight/2) > (imgTop-bodyHeight/2)){
 img.src = imgSrc;
 this.imgs.splice(j,1);
 }
 }
 }
} 

var img1 = new scrollLoad("scrollLoading");
</script>

希望本文所述对大家学习javascript程序设计有所帮助。

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